There are three main types of expected lifespans. Humans belong in type 1. Infant mortality is extremely low for our species and we usually all live quite long.
Type 3 are plants and marine animals. They have absurdly high infant mortality rates, but as long as they can survive that, they usually live up to their life expectancy.
Type 2 are the weird ones. The ones that will just randomly die. The mammals, birds, lizards, and so on.