Could humans bring back dinosaurs?

The short answer is no, humans cannot bring back non-avian dinosaurs like T. rex or Triceratops through cloning. The main reason is that dinosaur DNA has not survived in a form that would let scientists reconstruct a full genome. Dinosaurs died out about 66 million years ago, far beyond the practical timescale for recovering usable DNA.

Why cloning dinosaurs is not practical

Cloning by somatic cell nuclear transfer requires intact or nearly intact genetic material. For non-avian dinosaurs, that kind of DNA is not available, so there is no complete genome to clone.

What scientists can do instead

Birds are living dinosaurs in the evolutionary sense: they are avian dinosaurs and descendants of theropods. In laboratory research, scientists have been able to modify bird embryos to produce some dinosaur-like features, such as changes related to snout and beak development.

That does not mean a true non-avian dinosaur can be revived. It would only be a modern bird altered to express some ancestral traits.

Could a real dinosaur be recreated someday?

With current science, no. The closest realistic outcome would be a bird engineered to resemble some dinosaur traits, not an actual resurrected dinosaur.