DMT is very different from DXM and ketamine. Those are dissociatives, which are powerfully psychedelic but still profoundly different from a hallucinogenic tryptamine like DMT. But your point still stands - human beings and many other animals have an interesting neurological relationship with certain chemicals. There are receptors evolved in the human brain just for delta-9-THC, the active compound in the cannabis plant. And there are natural reserves of DMT in the human body released during times that coincide with dreams and near-death-experiences (NDEs).
edit ~ however, OBEs (out of body experiences) are similar in nature chemically to experiences caused by dissociatives