Genetic Evolution System: Only I Can Adapt

As of the year 20XX, humanity is on the brink of collapse.
Three years ago, the “Fulminare” appeared from seemingly thin air. They appear to be human in every way, only possessing physical gifts superior in every fashion, some of which even wield supernatural abilities.
Only with a single soldier are they able to subjugate entire cities, perhaps only a small force from their world has been sent, as though Earth is nothing more than a side project for them.
The United Nations is barely hanging by a thread, perhaps only by the Fulminare’s repeated demands of submission. All hope has been lost, except for one miraculous arrival, discovered in Death Valley, landing in a crater fit for a calamity:
A sphere, requesting to be bound to a host.
After countless tests and many deaths, a young, talentless man–”Seven”--is accepted by the sphere.
[Genetic Evolution System Activated.]
[Beginning genetic alteration.]
From a scrawny, small boy to an imposing man of perfect musculature, he shatters all world records from strength to speed, but even that is not enough for the Fulminare. He must adapt, evolving his genetic structure to face the overwhelming invaders.