You’re not deep enough yet, tides and earths core only exist because stars exploded billions of years ago and some particles eventually formed earth

Geothermal comes from friction inside the core, residual heat from planet formation, and radioactive decay. Since all elements heavier than hydrogen were fused inside stars, and heavier actinides like uranium are formed in second gen stars, and the inertia of dust that coalesces into planetary bodies including the earth and the moon originated from dying stars going supernovae, geothermal and tidal energy are products of stellar explosions, either inertial, kinetic, or radioactive. Tides are driven by the moon, whose energy is kinetic, stored from past supernovae

Planet wouldn't exist if stars didn't explode billions of years ago, checkmate.

Pretty sure if the sun stopped generating heat the oceans would freeze but I'm no astrophysicist.

This raises an interesting question in my mind, does tidal power make the earth get closer to the moon? Because if you got all the energy out of it, then the water wouldn't move, so I guess it's the same as gravitational potential in that sense, but I guess it's removing it, so less gravitational potential means either less mass (not the case) or less distance.