How did you determine that there was no ancestral lineage leading up to those fossils?
How did you determine that they suddenly appeared?
How did you determine that they are fully developed?
Here are the most developed vertebrates in all of the Cambrian.
That's it. Those aren't fully developed. They don't have scales, bones, jaws, fins, and many other features found in fully developed vertebrate fish. And we aren't even getting to the rest of the vertebrate phylum.
How can you say that these are fully developed vertebrates when you can't even find something like an amphibian?
Again, the Cambrian is a time period, not a type of sediment or environment. There are Cambrian terrestrial deposits. They are devoid of life. Why is that?
Why can't we find fully developed fish in the Cambrian marine deposits? How can that be?