You've stumbled upon the basis of the debate between free will and determinism. imo, we are merely under the illusion that we're making our own choices. The universe is one infinitely complex system of falling dominoes, with each choice and action just being the result of the parameters set by the ones preceding it. We are all made up of the same basic building blocks, and are thus just subatomic systems obeying the laws of thermodynamics... it just happens to be the case that when a system reaches a certain level of complexity, it is able to think about itself - we are quite literally the universe experiencing its own existence.
Why is this? I don't know. Nobody knows. Consciousness and 'the ability to experience' is one of the most elusive and complex questions facing science and philosophy today. It's my personal belief that there is certainly 'something' more to this whole cosmic experience, but I'm not convinced by religion's answers and believe 'it' to be something so vastly incomprehensible and foreign, we'd never understand it even if the mystery were revealed to us. It isn't something I like to think about too deeply, because unfortunately, it opens up an infinite regress of questions we will likely never have the answers to.