There is no question abut evolution. Even Pope Francis believes in it, and thinks people who don't are just looked upon as foolish. The origins are theories. Pope Francis simply states God created living things with the ability to adapt genetically. We cross bred species for years, and now manipulate DNA to make GMOs (Genetically modified organisms). We discuss rates of mutation and change, not whether it occurs.
Common Traits. Common Ancestor.
Think about your family. You and your closest relatives look more alike than you and your cousins. Likewise, you look more like your cousins than you do more distant relatives, and more like distant relatives that people on the other side of the globe. The closer you are related, by-and-large, the more similarities you share. Of course, these similarities extend well beyond the surface level, reaching into our genetics.
We see species changing over time. Species that lived in the past are very often drastically, wildly different from anything alive today. Trilobites, dinosaurs, giant sloths, baculites, etc., Isolated species lacking predators in some places that are gone from others.
Remnants of past generations as things with little use in animals. These are called vestigial. In humans, muscles of the ear; wisdom teeth; the appendix; the tail bone; body hair; and the semilunar fold, in the corner of the eye.