Why is Earth the third planet, shouldn't it be the first?

How do we know earth is the third planet away from the sun?

2006: a space oddity – the great Pluto debate, Pluto

Third Planet

Bad Astronomy “Orbit-clearing” planet definition calculated by

NASA missions may re-elevate Pluto and Ceres from dwarf planets

A Year Throughout The Solar System - Astronomicca

Webb telescope snaps image of solar system that's nothing like

Who Really Discovered the First Exoplanet? - Scientific American

ESA - 10 remarkable Earth facts

Solar System Answers in Genesis

Did Life Come to Earth From Mars?, Science

Third Planet

Life Finds a Way: How Netflix's Life on Our Planet Brought

Shouldn't We Fix the Earth First? - Universe Today