I had my wisdom teeth removed. will the remaining crowded teeth spread backwards by themselves?

Probably: Likely now that there is space, the teeth will adjust to more space.

No, unfortunately.: No, the only way to "uncrowd" or straighten the teeth at this point will be orthodontics ( braces or invisalign ).

Not likely: Having wisdom teeth removed will not correct the crowded teeth problem.

Sadly, not possible: The wisdom teeth were never preventing them from "drifting" back so their removal will not stimulate them to spontaneously move. There is also no force being applied to the teeth to cause them to move.

Not likely: Teeth want to drift forward, not back, with or without wisdom teeth. Crowding does not self-correct, it gets worse with age. If front teeth are crowded, ask your dentist to refer you to an orthodontic specialist for discussion of treatment options. You owe it to yourself to at least explore options.