Why is newton's first law of motion considered a law and not a theory?It is an unsupported idea. It is based on multiple observations. It has never been tested. It was validated by a singular experiment.

True, but heres more info

Explanation:

I think people consider it a "law" because it always happens and never stops happening (think, if you're on Earth and you jump, you will always hit the ground)

Basically, Newton's Gradational Law will always be followed as it is a law of nature that we have discovered :)