Who Invented The First Calculator Ever?

It depends on what you mean by "calculator."

Tally sticks and other markers were used for representing numbers in a mechanical way far before history began to be recorded.

The abacus has been in use for centuries. Like many such devices, its development was probably the result of the input from a number of people over a period of time.

A mechanism for calculating astronomical positions found in a shipwreck in the Mediterranean was dated to about 150 BC. The inventor is unknown. It was obviously a highly evolved device, so there were undoubtedly predecessors.

A number of other mechanical and electronic analog and digital devices have been used for calculation since. Some have individual inventors known to history, some don't.