Maybe a helpful visualization is one of the precursors to quantum field theory, Dirac's sea.
The idea is that you can think of a particle as sitting on top of the surface of the "sea" while an anti particle is represented by a hole in the surface, large enough to fit one particle. When a particle encounters such a hole, it naturally drops down into it and settles there. This essentially "destroys" both the particle and the hole (the anti particle).
So essentially the opposite charge, spin, etc of a particle and anti particle are a consequence of their opposition in their fields, not the cause for the annihilation.
(Not a scientist, grains of salt and all that).
I think when you consider the rate of advancement of any technological species, "roughly the same level as us" basically implies that they got started at exactly the same time. Even an extra thousand years of technological advancement would put them far ahead of us. A million years would put them unimaginably far ahead.
On a cosmic scale, that's nothing. That's a tight window and given the like 8 billion years that planets with the required elements have had to form, I would doubt that no other species had a chance to surpass us.