Yes, and it has been for 150 years and still the theories of evolution still provide the best explanation for speciation so far. Darwin came up with the first theories and since then more theories which are more robust have evolved from Darwin's ideas. Darwin has no bearing in the debate about the efficacy and fitness of the theories of evolution.
"... still provide the best explanation for speciation so far."
You have no understanding of the difference between evidence and a guess.
But you do?
Do you know the difference between a theory, a hypothesis, and a guess?
The theory is a framework of explanations based on the evidence which explains the observed phenomena and makes accurate predictions. It must do both. Or as you'd call it: a guess - if theories like Germ Theory, Atomic Theory, The Theory of Relativity, etc. are guesses.
The evidence are observations of the phenomena which supports the theory in its ability to explain the phenomena or to make predictions regarding the phenomena, or detracts from the theory in either way. So far, in 150 years,no scientist has been able to, despite many attempting, to debunk any of the current theories.
Do you have a better "guess" that explains speciation which includes geologic, genetic, morphological, and physical evidence and which also makes predictions which bear out as the theories of evolution have? No?
Then my statement stands: the current theories of evolution are the best explanations for speciation so far.
Stop cherry picking which arguments to which you'll respond and address each point and that might help your arguments' credibility.