Not a linguist but I read way too much on languages, AMA.
English has simple morphology (cases and the ways words are put together), but the syntax is really complex, and there are a lot of registers because half of our words come from Latin and a decent amount from Greek too. I would hesitate to say that makes the whole language any more different than others in terms of simplicity. Languages that are simple on one area tend to be very complex in others, and vice versa.
Here are some fun facts about PIE (proto-indo-european):
It was spoken originally around the plains of Ukraine, and it had a really complex (and unstable set of consonants). Simplified, it had p b and bh, for instance. Because there's a voiced aspirate series (bh) you would similarly expect an unvoiced aspirate series (ph), which didn't exist. So the system collapsed in the various languages into a more stable form, leading to a lot of the differences between, say, greek, german, latin, sanskrit, etc, depending on how they stabilized the system. Most of the ones in europe merged together consonant sounds. In India though, they added the missing ph series to stabilize it.
PIE also only had one vowel (e), which changed forms depending on the grammar (this is called ablaut). This is similar to how English uses sing, sang, sung for tenses, though this developed differently and isn't related to the PIE ablaut. In old english, there were markers that indicated tone (like how we use -ed for past tense now); these markers were vowels, that the vowels before them then changed to mimic. For instance, if sing is the current tense, then singu → sungu would be the past tense. Over time the final vowel got dropped off (this is what happened to mess up English spelling and lead to the "magic e"— the 'e' in words like 'knife' was originally pronounced, but people got lazy and dropped it), and all that you're left with is sing vs sung, which speakers just memorize or reanalyze as the new tense. This isn't the exact specific example that happened in English (it was much more complex), but the idea stands.
Then we get into fun with vowel lengths: English used to have long (literally pronounced twice as long) and short vowels. In 'closed' syllables like "night" (the gh used to be pronounced like the german "ch" in "bach"), the vowel was short. When the 'gh' stopped being pronounced, it first lengthened the vowel. Long vowels then become dipthongs— in this case 'ai', which is why "night" is pronounced like "nait" instead of "nit".
The long-short distinction is another reason english spelling is so bad. words like "knife" had a long vowel, hence "ai" pronounciation, whereas other words like "kit" had a short vowel that didn't change (much). But when English spelling was being standardized, they didn't mark whether or not vowels were short or long and wrote them all the same, so now you just have to know whether a word has a short or long vowel.
tl;dr I need a better hobby because I waste way too much of my life on learning useless things
