I don't know if I should let the player skip around levels from the level select, or if  I should lock levels until you beat the one before it. Any thoughts?

I guess make a level selector but put a tutorial also to how to play the game

I am talking level selector because then players will be allowed to explore the mechanics off your game very fast and that's what people usually do in jams they only play the game for like 5 mins and then rate on the basis of that

But if you want like a storyline then the locking one would work