It’s possible, but imagine you find a decrepit alien structure on the shoreline. You’ve never encountered it before. Do you think this broken down structure is going to easily give you answers? Do you think you’ll be able to recreate its building techniques without guidance to build a fully working one (even though this one may be incomplete)? I think this scenario is less likely than being trained by a fellow human. Unfortunately, unless there is evidence of genetic admixture it may remain uncertain.