I'm not a huge fan of pico-8 games, but man, you did some good work with it!
I liked how many little things you managed to put in there! Sheering sheep, putting fences, the shop (actually it would make sense to sell any wool I have automatically at the end of the wave, but I'm nitpicking). The game was a bit difficult for me- the wolves got me pretty early (consider healing player between waves, maybe?).
The graphics and sound were cool! Felt like a proper game from 1989!
The use of the theme- on point. I couldn't save them all (I couldn't even save myself), but trying to do so was the driving force of the game, and everything the player does! Every player decision was centered around that!
Over all- well made game!
Oh man! I just noticed you joined the jam for the first time! In that case- congrats on getting through to the end, and focusing on the theme (first timers often use the theme vaguely- not you!).
And one more thing. Consider other game engines. You obviously have some good gameplay ideas, and pico8 might be a bit limiting for you. Sure- godot or unity will take time and effort to learn, but I think you'd discover it was worth it!