If things are such that aliens send probes to any such planet as ours they would be concerned about negative consequences and put great effort into ensuring they could not be discovered by _any_ potentially threatening species.
This precludes any of the forms you suggest, as any species capable of sending such would also be more than advanced enough to ensure we wouldn't discover them and that they wouldn't fail at the rates claimed.
Even if we presume many many species sending such, there's the issue that they wouldn't be bothering with us in this way and would either have already conquered us for the resources to fight each other etc. (And even if not fighting they would be aware of each other as a result of these supposed visits).
There's no reasonable explanation for subterfuge which is the only answer ever given for such questions of "why have they not made direct contact?" Right?
If they don't have FYL then it's ridiculous that they'd send what are effectively tiny scout ships that don't have stealth tech to avoid the Other Aliens and that crash at alarming rates With Living Pilots inside...
Really...
Just look at the claim objectively and it becomes obvious it's absurd.
Do I need to say more?
If things are such that aliens send probes to any such planet as ours they would be concerned about negative consequences and put great effort into ensuring they could not be discovered by _any_ potentially threatening species.
This precludes any of the forms you suggest, as any species capable of sending such would also be more than advanced enough to ensure we wouldn't discover them and that they wouldn't fail at the rates claimed.
Even if we presume many many species sending such, there's the issue that they wouldn't be bothering with us in this way and would either have already conquered us for the resources to fight each other etc. (And even if not fighting they would be aware of each other as a result of these supposed visits).
There's no reasonable explanation for subterfuge which is the only answer ever given for such questions of "why have they not made direct contact?" Right?