how does liking someone work?

is it the opposite genders that attract people to each other? im confused because when you first go on dates and talk to each other, you people aren’t romantic yet, not “flirty” since yall arent comfy with each other yet. as you hang out with each other, you treat each other the way you would treat your own friends of the same gender. when hanging out (before dating), theres no diff to how you treat the other party so how do you end up falling in love/liking the person? also, this especially conflicts me: when two people (M and F) text, they text about topics which interest them to know one another, which is exactly how friends text each other. so my question is how do people have a crush / know that they like the person and want to know them better just based off texting??