I'm not sure about shanks or tanks. But the fallen revere the servitor as gods. I think they are some form of AI. They have their own language. And they also share some sort of religious bond with Archon priests. So yeah they are alive and/or sentient but perhaps not as we think they are. I'm actually pretty damn facinated by the servitors.

I think the answer is: "Not really either." As in, neither alive nor sentient. To be sentient is to be self aware on a level beyond mere robotic approximation of intelligence. So - Exos are sentient, as they were seeded with consciousness (we are learning that at least some were seeded with the consciousness of humans - Cayde-6 was once a human mercenary), and Ghosts are full AI's and thus sentient. But Frames (the robots in use around the Tower and in the Reef, such as the Postmaster, Bounty Handler and both the Vanguard and Crucible Quartermasters) are not sentient, they are highly advanced robots with limited learning capabilities who can develop some degree of personality quirks over time by mimicking behaviours they observe. Frames are also distinguished from Exos in that they have a distinct rectangular/oblong head, and their names seem to always end in a two part numeral (99-40, 55-60, etc) - whereas Exos have a more human shaped head and have a single numeral. I say so much about Frames because in the new Quests, there is flavor text in the form of quotes by various individuals, including Ghost. In the mission to defeat Sepiks Prime, Ghost states that he has wondered what makes the Servitors so special that the Fallen would outright worship them, but further scans have shown them to only be "hyper-advanced Frames" - so not even truly sentient. Shanks are robots with roughly dog-like intelligence, so again, not sentient. Tanks I do not really know. I wondered for a while if they were piloted by Fallen, or just a large robot chassis - like a Shanks big brother. I strongly suspect the latter, which certainly supports them being non-sentient robots as well. The key difference with the Vex is that not only are they sentient - possibly possessing a fully evolved Artificial Intelligence (I say possibly because of the next point) - but also contain biological components, albeit ones we are not familiar with. Ghost comments on this in spoken dialogue in game. This means they might be actually be some form of organic life and thus not "Artificial" Intelligence at all, only having come to appear robotic/synthetic later in their species' development. Kind of like Borg, maybe? there is definitely much more to them than we currently know. At this stage, there are as many (if not more) mysteries as there are answers, with a little bit more revealed with each new set of Grimoire Cards, and a LOT of new data in TTK overall. Above is merely what I have come to understand from my experience - new information may well confirm - or prove entirely wrong - what we think we now know. Hope any of that helped! =)

I don't think shanks are because [spoiler]in the one strike they mention the fallen build them from different parts[/spoiler] The servitors I think are alive cuz they [spoiler]worship them don't they?[/spoiler]

The are robots created by other robots created by an even greater robot no life at all. Exos though dont live the too are robots but society in the destiny universe has accepted them to be just like a human. It all depends at how you look at them.