>Left: Equivalent to Homo heidelbergensis
>Right: Equivalent to Homo neanderthalensis
>Current SpongeBob: Equivalent to Homo sapiens

Any further questions

Primitive
- No eyebrows
- Fucking giant and sharp fangs
- Baggy eyes
- Less "solid" artstyle from earlier episodes
- Loincloth that only covers his crotch area
- Pissed off look
Gar
- Unibrow
- Single small and buck tooth
- Big and happy eyes
- "Solid" artstyle from modern episodes
- Clothes that cover him up almost as much as normal Spongebob's outfit
- Not-pissed look

There's certainly similarities, but the differences make them look rather opposite to each other.