Niels Bohr -energy levelsWatch
Why is the energy level closest to the nucleus the lowest?
Imagine the electron is a rocket in orbit around a planet (the nucleus).
When rockets launch they park themselves in low orbits. If they want to get further away from the planet then they would need to burn more fuel(increase kinetic energy) and this would put them into a higher orbit.
You could also say the electrons have more energy higher up so they can resist the pull of the nucleus. But I dont know if that is actually true.
I hope this helped.