So you're a nihilist but you don't believe in predestination? You don't think that some people are uniquely born good or evil, that we all choose the roads we follow and aren't lead down them through suggestion from our biology and environment?
What I'm trying to say is how do you know there's not something in that mind and body of yours that dictates your freewill like a program? From a slight twitch in your thumb to the words you say, how do you know it's not just a reaction? How do you know the choices you make are not already decided beforehand by fate itself?
Say there's a 4 dimensional being that is capable of going from the beginning to end of the universe and interacting with it. Say they did nothing and just watch the universe play out again and again, would it always turn out the same? Is anything completely random? And if there ain't no 4 dimensional time wizard, then how can anything change from its current course of actions?
I think the Universe is made out of 2 layers, cosmos and chaos. The cosmos is the matter, energy, etc; elements that, if the beginning of the Universe is always the same, it will always play out the same. The cosmos has no agency and will always follow a predictable pattern. The chaos are beings of higher intelligence; animals that are smart enough to make decisions on more than instinct. A chaotic element can take a different path, regardless if the circumstances of its inception are the same. Or, at least, that's the best way to describe it.
So no, there's no such thing as predestination. Even if something is concieved in the same circumstances, chaotic behavior can lead to different outcomes. For example, a poor person can play his cards right and become wealthy, and a rich can gamble it all away and become homeless.
Free will is a weird subject. There is no free will, as in many of your decisions and choices are heavily influenced by your biological drives. Things like mood, needs, etc. Even if you have 100% free will, you still have to play by the rules. But fate? No, the Universe won't play out like a prerecorded tape.
So yea, that should answer your question, if a 4th dimensional being would watch a universe play out over and over again, and the conditions allow the agents of chaos to influence the universe in a way (ie, intelligent life is created), the Universe will play out different.