What is the theoretical probability of getting heads? That's it nothing else just heads ... is it like 50/50 shot? Or 1/2?

Answer: The theoretical probability of getting heads is just 50/50, you were right.

When you are flipping a coin, there are two equally likely possible outcomes. Only 1 of those outcomes is heads.

Therefore, the theoretical probability of getting heads is 1/2, or 0.5 or 50% or we often just say 50/50.