I mean, the standard for Interact has been either E or F in 99% of games, and Z or Enter is RPGmaker or RPGmaker adjacent games, so maybe either, though RMB does remind me of old Adventure games.
The water took me a little to find out, since I clicked far away rather than close, and got nothing.
Also, something I didn't mention initially, In-action or missed actions that didn't actually do anything still cost stamina.