Unfortunately, a 6 mana 5/5 isn't good enough, even if it can randomly end up attacking as a 10/5
Frodo, Adventurous Hobbit features Vigilance as a keyword and also encourages you to gain life
Slimefoot, the Stowaway Slimefoot, the Stowaway is a more classic saproling commander, and you can pump saprolings out by paying 4 mana
You have to sculpt your deck in such a way to make the ability consistent, which is half the fun of the card
WANDERING ARCHAIC Wandering Archaic is far more heavily played than most cards I look at in my 5 Underrated Commander Cards articles
Perhaps you love that kind of adversity, and you know your playgroup runs very resource-efficient decks with varied answers for permanents that are unlikely to be completely stalled by a turn-two Sire of Insanity