On many fronts from epistemology, psychology, and neuroscience, we are geared to form reliable beliefs and these processes through the wonders of evolution, are themselves reliable.
It is true that some have the ability to more often produce more beneficial beliefs and that some have disabilities.
On the whole, these don’t describe anything at issue here.
There is then a sense in saying there are “default positions” but not as hoped by those using the term. Our initial beliefs are the only beliefs warranted until some greater reason to doubt them exists. Since the sciences suggest no one chooses what to believe or how our beliefs will form, there’s no other sense to the application of such a term.
That our beliefs may be mistaken or that we may not be able to account for what we believe or why we believe is irrelevant to being ethical, responsible, and diligent with our beliefs. On this view, the only mistake we can make is not being open to having our minds changed. The only other fault we may have is again ethical in, knowing all of this, suggesting someone ought to be human in a way we are not and suggesting they should doubt their beliefs merely on our sayso.
One must have warrant for every belief and every doubt, and having no good reason to believe is likewise no good reason to doubt, just as having no good reason to doubt is no good reason to believe.