I’m an engineer,

And thus, you have no relevant expertise in the matter.

You cannot develop a ‘science of history’.

There is, in fact, a historical method. Sure, it's not scientific, it's not empiricism, but it also doesn't claim to be, so your criticism here is entirely beside the point.

As an example, modern Biblical ‘scholars’ believe that there exists a mythical book called Q that is the source of Matthew and Luke...

Well, it's the most common opinion, but it's far from universal. There's Markan priority, Matthean priority, and so on. However, these scholars are simply trying to understand how the gospels were written. This is, at worst, irrelevant, and at best, laudable.