Bullets

Alex dived through the closed window, smashing the glass and even pulling some of the frame out of the wall. He fell from the second floor like he was doing a belly flop into a pool, with his body close to being level with the ground.

The speed of the fall was enough to seriously injure Alex, even with his status as a User, and he knew that. Unlike other Users, Alex didn't suddenly get stronger when his ability manifested, he has to absorb life force to get stronger, this means he's barely better than a regular human when it comes to his [Constitution] even though he already raised it's stat value to 2.

[Physique] may have helped in the this situation as well but it's stat value was still just a 1, meaning Alex was nothing better than a regular person, in fact, he was even weaker than a regular person.