“It’s a prototype”
“It’s an MVP”
“It’s a Proof of Concept”
“It’s an evolutionary product build”
“This is the beta”
Whatever it is you decide to call it, everyone on the team needs to decide what it is and who it is for. You need to define what you are delivering.
One person having a different notion of what it is during the delivery of the project will only yield confusion during the work that is being done to deliver the final solution.
You can switch what your delivery definition is but this should always, always be done as a team, and not by one person on the team.