The tree of knowledge of good and evil

If Adam and Eve eating the fruit of the tree is what introduced sin into the world, then why would they have been tempted to eat it? Like Jesus taught that it’s not just the action that is sinful but to even have the thought is sinful right? So they sinned the moment that they even considered going against gods will right? (Referring to Matthew 5:27) How could they have even considered going against Gods will before they were sinful? Also people say that the reason sin exists is because God desires us to have free will. So to me that says sin is a byproduct of free will, and if free will is good why would it have led to something so bad? Doesn’t that go against Jesus’s teaching about good and bad trees and the fruit they produce? Was he referring to the trees in the garden at all or is it just a coincidence? I mean one tree led to death and suffering the other gives eternal life so I think there may be a comnection there. Let me know what you think