The first organisms were
Chemoheterotrophs
The first living beings were prokaryotic, like bacteria. They were single-celled. Nucleic acid core consisted of naked DNA. These living beings were present in the environment of soupy sea having abundant organic molecules. Nutritionally they were chemoheterotrophs. They absorbed the organic materials from outside both for body building and liberation of energy. Respiration was anaerobic since free oxygen was absent in the environment.