Heya, thank you for this lovely review! :)
Yeah, now that you mention it, the bounce off mechanic is pretty similar to Hollow Knight's, didn't think of that, haha.
Regarding your question, I can't think of something specific that inspired that mechanic. I'm very interested in eventually creating action platformer games with interesting and fast movement, so I'm trying to experiment with that in game jams.
The theme is 'earth', and unlike water, earth commonly floats in platformers, so I thought it would be fun to combine the attributes of earth platforms and water in order to let the character "swim" through the level and get higher up that way.
As for the launching mechanic, the original idea was to allow the player to jump higher up with it, encouraging them to dig instead of just jumping, but after some thought I realized it would be boring on its own, as I'm just forcing the player to dig in order to make higher jumps, which is why I've added the flowers, I think it makes it much more interesting.
If you're interested in another challenge with interesting movement, you can check out my previous game. It won the previous mini jam and I'm really proud of it :)