It's about the core of the toy, Like really simple mechanical things tend to appeal to boys, and soft things that resemble like, a baby, appeals to girls. And before anyone pops in with that "excuse me I was into paintball when I was young" shit, we're talking about extremely early fundamental shit. Things you don't even remember before you developed a personality.
Or in other words, I fucking loved gear pumps when I was a kid. Dad had a few lying around and it was just a bunch of gears that if you put them together right, would spin around perfectly and push liquid through.
It's why you don't see any baby dolls with ninja fighting action and plastic laser beams that launch out of its eyes. And why most action figures are going to be hard plastic with spring loaded kicks and punches. It all boils down to lizard brain shit that goes back to us crawling out of the evolutionary sludge.
Rhesus monkeys aren't fucking human, they have a different DNA order (they have extremely different results even if they have the same genes on some aspects), they don't use social cues, they are more isolated, are herbivorous, have smaller social groups and aren't as aggressive as us, comparing humans with them is like comparing cats with dogs or cats with civets because they are four feet animals or have similar origins, even if they behave completely differently and normally eat different things.
Chimps which are closer to us use more social cues and they don't reflect the soft cuddly thing that rhesus monkeys have, even more when this can be a misinterpretation around what the monkey is reacting, it's very likely that rhesus monkeys believed that the thing they were grabbing were literal fruits because of the color and the soft aspects around the toys, something that female rhesus monkeys do specifically, the same as some animals having a more specific way of seeing things in males in comparison to other animals or other specific animal quirks (most of these aren't hormonal but genetic, these aspects don't change with the use of testosterone or estrogen, even more when these two hormones cause the same violent reactions, which is the real reason people who use steroids are violent, it isn't because they have extreme t levels or extreme estrogen levels, but that they have both of them on unnatural levels, causing fits of rage thanks to this excessive quantity). These things are normally variations in specific species to reflect on certain aspects or natures, not general aspects, extrapolating these things on all animals is like seeing fish and believing we can change sex because they can do it or thinking that we have multiple color ranges like octopus, it's unrealistic and doesn't reflect on anything.
Humans in comparison are more violent, as humans we hunt, attack in group to destroy bigger things than us, take care of our offspring as father and mother and use more violent attitudes in general than more general monkeys who eat fruits and seeds, instead of the more meat based diet that we have.
As humans we like to do violent things before our child caring instincts kick in after having a kid, most kids behave violently with their toys and that's the reason before the age of 1 they behave exactly the same (stacking stuff and dropping them), most of the things that change behavior is because people autistically make someone behave specifically and forget the the acts that go against that narrative of separate natures, something that even if understandable, isn't a real way to uncover our behaviors and interests, even more when these things change over time and aren't a biological reflection of anything.
Our sexual dimorphism became the way it is for this reason, it got reduced and became more general as an aid for the complex aspects off all our life, instead of the more specialized aspects of monkeys, even more when our vulnerable children and our social groups made most of the child bearing tasks a very general and total aspect of humans, instead of females doing all of the job which happens because monkeys aren't dependent for 10 years with constant watch, just needing a year or less to be independent and already not being completely dependent by the mother since they are born.
Another reason rhesus monkeys behave like these is because they fight for mates in a polyamorous setting, so they instinctively start doing these behaviors, humans in comparison are always monogamous (something that was proven with dna testing) and hunt on an extremely active manner, so in comparison babies in general already are more active and behave more similarly if you remove socialization. If you wanted a more general comparison for humans, owl monkeys are more similar to us.
Reptilian brain is the literal fighting-run response of our behavior and our interest to kick shit, not general jobs and general interests, these things happen at genome level when an animal has certain situations and evolution scales before hand, they aren't a general instinct which happens on all animals at all, unlike fighting instincts.
You shouldn't put human aspects on animals in general, they are animals, animals don't do these things because they behave like a human kid, they behave like these because the mother only does childbearing and because they specifically find fruit, instead of the male which always tries to defeat opponents to have access to these females on a matriarchal society, humans in general don't comply with any of this and for this reason these aspects have changes culturally and socially. Using these studies as justifications just causes more problems at finding our real behaviors, functions, situations and more, something that affects us in general.
And that it's literal tranny logic. because a different species does something doesn't mean that others can do it or do it on the first place, a boy and a girl will still be a boy or a girl by biological reality, using stereotypes to correlate one or the other only generates people who believe these aspects as as a reality or idiots who use these fundamentalistic ideas to attack everyone else.