Before there were genes there were simple chemicals that had to divide and replicate. A gene is a fairly complex thing and it had to come into existence from something simpler. The first organisms probably had dozens of genes, not one. Well, the fossil debate is old and tired. Evolutionists say there are plenty of transition fossils, for example, the horse.
Critics say there are still a lot of gaps.
Whatever is true about bones, genes are complete. They are protected from the elements. And the patterns, complexity, and groupings of genes between simple organisms and us show plenty of continuity. That is what makes the genetic evidence so important. The issue is not materials.