You might be right about that.
The Cambrian explosion is that evidence, as you yourself say, if there were no ancestors (and there's no evidence of any) then "these animals would have to instantly spring from nothing", I wondered when you'd begin to get all this.
The only way to identify ancestors for Cambrian animals is cladistics, compare morphologies as best we can from the fossils, but there are none, none of the 20+ phylae (each of which appears for the first time in the Cambrian, each of which appear almost at the same time) have any evidence of being related at all, no ancestor fossils are known that represent a common ancestor for even one pair out of the 20+ morphologies. For example trilobites and anomalocaris each have keratin body parts, so there will be a common ancestor too that represents some of the earliest animals to have evolved keratin production.
So a trilobite and an anomalocari are descendants from some earlier common ancestor that has evolved (or itself inherited) the ability to synthesize keratin, lets look at each of these:
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Yet despite obviously having keratin we find no trace of any of the expected thousand upon thousands of generations of either of these. The above animals came from different parents, I think we can agree on that, but as we go back we'd
expect to see an ancestor from which each of these bifurcated, and that ancestor would have already evolved keratin in order to pass on those genes to these eventual descendants and so those ancestors would be as readily fossilized, particularly when we find fossils of tiny soft bodied animals in the strata that we know represent the prior time frame.
Yet we do not, we never have, not only have we never found a credible common ancestor we've actually never found any ancestor for either of these, and this is just two from among many many others - that all just appear in the Cambrian.
Nothing you've said or shown us changes the fact that there is no evidence of ancestors, therefore as a rational skeptic I refuse to believe they evolved, the evidence is simply non existent.