A creature card with changeling is just as much an Elf, a Dwarf, a Sliver, a Goat, a Coward, and a Zombie as it is a Shapeshifter
You might get sometimes blown out by getting 1/1 Squirrels instead of larger things that opponents want to give you, but for the main part youre in control
Whenever Slime Against Humanity is cast, it creates a 0/0 Ooze Creature Token, then puts +1/+1 counters on it equal to the number of other Oozes in your grave or Exile, plus the number of copies of Slime Against Humanity there too
If you don't know what to look for, you could easily mistake a Beta card for an Alpha card
Maybe the issue here is Ephemerate
It also saw play in Standard too as a way to close out an otherwise unmoving board state