What does the ending mean?

Just finished Inside. My response was:

"Seriously? That's the end?" I'm sitting in a blob on a beach.

Did I miss something? Do I need to do anything during the game to get a different ending? If so, can I do those things by skipping around the checkpoints and replaying the end?

If not, what's going on? How is that a proper ending?

The ending (and the title) of Inside suggests that the boy you thought you were playing as all along was really being mind controlled by the real player-character: the blob. The game sets up a few hints along the way:

• When you're plugged into one of the mind control "helmets", you can control somebody else. The blob has several of the mind control machines attached to it, which implies it has some serious brain-enslavement capacity, it needs a lot to keep it under control, or both.
• The mind control effect can be chained (when you control one person through controlling another person). This establishes the idea that the boy could just be another link in the chain.
• Mind control subjects aren't susceptible to many of the injuries that would stop a normal person, and you miraculously survive being drowned at one point. (Granted, the boy is able to drown before this and can die from falls the whole time, but I'll chalk that up to ludonarrative dissonance from keeping the gameplay challenges reasonable).
• The boy's actions stop making sense once he's in the facility where the blob is, and he tries to get away from it when it grabs him. The blob was unable to escape while the mind control devices were attached and needed to control somebody else to get them off. Once they're off, it stops controlling the boy right before consuming him.
• During the secret ending, you unplug an antenna-like device related to the mind control machines, before the screen goes dark and you lose control. This is the blob (and by extension the player controlling the blob) losing control of the boy.
• The majority of normal people are under some sort of mind control, and people who aren't controlled are killed. This is because if you're not under the scientists' control, you're probably under the blob's control, and it's trying to get out.

So with the twist explained, what the heck is up with the blob? Why does it exist? Why was it trying to get out? My theory is that the blob was created as part of a secret mind control program, and that similar to how the fused mass of bodies gives the blob super strength, the minds of the people within the blob are also combined and give it enhanced psychic abilities. The scientists are either using its power to mind control the populace, or they're controlling people with the technology they've developed out of a need to keep the blob contained, since they know it's trying to control people to get out.

Why does the blob want to get out? It's clearly intelligent, as it solves puzzles on its way out of the facility. Maybe the scientists were experimenting on it and it lived a miserable existence, which would be supported by the sounds it makes and the inhumanity of a pile of living human flesh. The blob may have wanted to die; while it twitches a little at the end, those could be the death throes of the blob which may have needed its tank to survive. Possibly, it just wanted to enjoy its freedom on the beach and to escape from Inside.