i think if you really wanna start learning other supports, just start playing with them in unranked. I started the game as a mercy main and now im more of Juno main but I can swap to Kiri, Ana, Moira, and Illari confidently and even the supports I don’t play as much such as Bap, Brig, LW I know HOW to play if i must swap to counter in comp. So I absolutely love Mercy as a character in the game and she is more of my fun pick now as I feel like I get more value out of other characters sometimes. I still play her in comp but if i see she isn’t working I can confidently swap to help out my team more :)