The first cell on the earth were Prokaryotes. Cells are divided into two types, whether they contain nucleus or not. The Prokaryotic cell does not contains contain true nucleus and cytoplasmic organelles or cytoskeleton.
Prokaryotic cells were smaller as compared to eukaryotes and were simpler as eukaryotes are complex.
These cells appeared first over 3.8 billion years ago approximately 750 million years after the earth was formed.