Is time an invention or discovery? Is it an arbitrary tool for measurement and humans' systematic perception?

If we believe in either theories of ultimate-fate-of-universe (including expansion theory, string theory, big crunch or cyclic theories etc.) time would be either indefinite (e.g. in case of expansion theory) or zero (in case of big crunch and cyclic theories). When time gets indefinite, it actually becomes equal with 0 time. Now tell me if it is a discovery or invention and if it is only a tool for measurement and understanding aging humans and phenomena? Thanks everyone!