Together with Ajani, Nacatl Pariah, these form the trifecta of absolutely unfair cheap white creatures from Modern Horizons 3 (honorable shoutout to Phelia, Exuberant Shepherd)
For just six mana, Seshiro provides what is essentially a permanent Overrun for all of your other Snakes, and lets you draw a card whenever one gets through for damage
Proxy Kings is a great way to round out a deck, though far from the best option if you want to purchase a proxy deck from scratch
I would like to stress that Green actually does have a lot of creatures in Ice Age
White in MTG is known for its ability to clear the board, and currently in the Standard format alone, there are ample ways of removing your foes threats in order for you to take back control and win the game
Additionally, Jim Hawkins can move to a new location for free whenever one is played