Evolution is based on science. Science is not a god, or a movement, or even a set of beliefs. Science is a process. It allows that human beings can make a hypothesis, set up tests, allow for variables and check for bias. Afterward they can reproduce results when the data shows it can be done.
Evolution of simple forms into more complex forms is seen in many more examples than just how human beings are made. It is called Bottom up engineering, as opposed to Top down. With evolution, people can look at how many things evolve. Language, for example, begins with a few utterances, adaptations are made, some changes are dropped over time, the environment and organisms using the language affect it, some rules apply consistently. Language evolves. Also, one can look at how something like a city starts with just one dwelling, then is built and changes over time into ever more complex and larger sets of buildings, roads, infrastructure and machinery. Many systems can be understood to have evolved from bottom up structuring, everything from one celled organisms to fully inter-connected forests from tiny seeds.
Evolution, then, is more correctly described not in the restricted understanding of how human beings and other primates share a common ancestor, but from the obvious observation that everything, whether created or not, is seen to grow from simple to complex forms. Even a watch being taken apart does not start with the watch emerging in complete wholeness to be deconstructed. Some things are designed, of course, but there is an infinite regression in such top down design. One can see that yes, there may well be a designer, but who created the designer? With science, repeated experience tells us, that organic growth can often be easily observed to start with a seed, become a tree, and arrive at being a forest.
Evolution, then, has many examples throughout the cosmos, to bolster its veracity.
Another set of inquiry could lead one to question whether science is biased. It often is, but the beauty of science is that it is a method of challenging perceived reality that is ongoing and self correcting. In the case of evolution, one can debunk claims that the earth is very young by examining fossils, plate-tectonics, ice age geologic features and much more. Also easy to debunk is the notion that humanity “arose” from apes, when in fact, both arose from a common ancestor.
Sharing a common ancestry does not require for no other forms to exist. Most animals can be observed to have shared traits, shared skeletal features, such as the tetra pod limbs that so many animals all have in common. It is not easily explained why so very many creatures would have a three part fore-limb, and a five digit “hand” that is seen even under the fins and flippers of marine mammals. The bilateral symmetry common to vertebrates found everywhere is a vital clue to how these forms all share slowly evolved traits. Then, there is DNA. The building blocks of biological life are real, and are used every day to gain knowledge. All organisms share DNA, no one refutes this.
Finally, one must be skeptical of any discomfort faced when a theory is called into question. Why would so many people be completely comfortable with all historical findings in vulcanology, for example, or with knowing the stars are distant suns, but be uncomfortable with science that explains well our shared animal origins? The answer is clearly that some answers found through science challenge the cherished idea that human beings are made in the image of God.
Many scientists marvel at this, as it seems far more astonishing to belong to the whole Cosmos, and comprehend that perhaps ALL is “of God’s image.” However, there is nothing in the amazing and grand scheme of all cosmological evolution that suggests human beings are not a very wondrous and unique species. It is the cosmos itself in all magnificence and diversity, that makes most human creation myths small by comparison.