Starter is connected but doesn't fully engage. just one click no whining

I recently have been having issues with my Van not wanting to start during cold, damp weather. I have replaced the Distributor Cap with new as it has build up on each of the prongs on the inside of it telling me there was moisture getting inside. Then I have also replaced the starter as it was just spinning and never fully engaging (only after a dozen or more tries would it kick over and van would run if i was lucky). Though this new one for my 1995 Astro Cargo Van 4.3 6cy engine isn't even spinning. It just clicks and that is it. If i pull it off and hook a battery jumper on it to test it i can get it to fully engage if i positve the big screw prong, negative cable to the head of the starter and then run a copper wire from positive to the (can't remember name of this one) small screw prong. If i do not run the copper wire between the two and just clip the Positive battery cable from jumper to both prongs it just does the one click and then stops. My battery has enough juice to turn it over as it did the old one i had and plus it has been checked at that time and is showing a good charge.

We have run out of ideas as to what the issue maybe. Would you have any ideas as to what to look at next? Wondering if there are different models that are sold for this starter and maybe i have one that doesn't fully function on my van, maybe a electrical issue that we have not thought of, or something wrong with this brand new starter (which im thinking most likely is not the case).

Thanks for your help