One characteristic all reptiles share is that they are all cold-blooded.
Reptiles and birds share enough common characteristics to be classified in the same clade called Sauropsida, which includes all modern reptiles and birds.
All reptiles share several key characteristics including having dry and scaly skin, being cold-blooded, laying shelled eggs, and having a backbone. Additionally, most reptiles have four legs with clawed toes or no legs at all.
All reptiles are diapsids. Mammals (like you and I) are, in contrast, synapsids. So in that respect all reptiles are alike. However, I would not say they were all alike. Snakes are reptiles but lack limbs. Alligators are also reptiles, as are lizards. Tuatara, gavials, amphisbaenids, and tortoises each represent one of the four main modern orders of reptiles. They share some characteristics--just as you and I do, but I would not say they were all alike.
No, humans did not evolve from reptiles. Both humans and reptiles share a common ancestor from millions of years ago, but they evolved along separate paths.
no all reptiles does not have ribs
A heart! respiratory systems, all are heteratrophic organisms, all use sexual reproduction (with a few exceptions here and there.)
Yes, mammals, birds and reptiles are all vertebrates.
Mode of reproduction
Marsupials are mammals, so share all features with other mammals. As well, they are vertebrates, so share the characteristic of having a backbone with birds, fish, reptiles and amphibians. Like birds and reptiles, mammals breathe via lungs (rather than gills), and like birds, they are warm-blooded.
Yes, all Reptiles do have scales.
No, they are reptiles. ALL turtles are reptiles.
Yes all rattle snakes are reptiles.