Not nearly that simple
Enzymes (catalytic proteins) are extremely specific to particular electronic configurations of particular elements and molecules. It's not just possible to just substitute one element for another, not even similar ones like Phosphorus and Arsenic. The enzymes and proteins have to be altered so that the substitute becomes useful, rather than a poison. The electronic balance is so finely-tuned that living organisms even select isotopes, rejecting the heavy isotope of Oxygen, Nitrogen, Carbon and especially Hydrogen. The energy levels are very slightly wrong, and enzymes incorporating the heavy isotopes don't always work properly.
Take haemoglobin (the red iron-based oxygen transport in our blood). There are three similar substances found in other living things. Insects use a copper-based molecule. Some marine worms use a cobalt-based one. Chlorophyll, which has a different role, is a rather similar molecule based on Magnesium.
Haemoglobin is the best oxygen transport molecule, and Iron is as abundant as Copper (maybe more so) on dry land. So why haven't insects evolved to utilize Iron for their oxygen transport?
I imagine that the sequence of mutations necessary is unlikely, and the intermediate forms that would be necessary never found a niche where they could survive and evolve, due to competition from un-mutated insects. Or perhaps the intermediate is such a poor oxygen transport, that the mutation is only viable in a tiny marine common ancestor. Also, although copper-based blood works less well than iron-based blood, it's probably less of an issue than body design for insects (with exoskeletons, which rules out lungs, restricts oxygen supply, and places a size limit of a few inches on all insects). In the case of life with lungs, haemoglobin would offer a much greater advantage, making large life-forms, and even large flying life-forms, possible.
Birds, by the way, have a subtly different haemoglobin protein to the mammalian version. Also iron-based, but the big protein framework surrounding the Iron atom is subtly different. That's how some geese can fly at the altitudes where we need a pressurized environment to survive.