Your interpretation is a bit wide of the mark. Inanimate things do not appear to work under purely deterministic principles, at least at the quantum level.
The accepted version of Everett's (https://en.wikipedia.org/wiki/Hugh_Everett_III) view in "Many Worlds" as a model is that every particle constitutes an observer. But the more particles are involved, the more the mass will behave like a macroscopic measurer.
If one particle bounces off of another, the effect is determined by the interaction of the two particles as waves, so it is just as uncertain as our human observation via an instrument would be.
But we do not observe one particle as it bounces off one other, we see objects with significant mass collide.
We don't see uncertainty because two more uncertain things together are more certain than each uncertain thing separately. Simultaneous probabilities do not add, they multiply.
The uncertainties for each particle involved in a macroscopic physical event all multiply, and since all of them are probability distributions with values less than one, the result quickly gets very close to zero uncertainty in the resulting outcome.
In other words, as far as "Many Worlds" goes we are not special because we think, we are just special because we're big and we stick together.
The worlds that accommodate our macroscopic experiences are more likely as "pasts" for future events. All the highly unlikely worlds in between also exist, but they readily merge into more likely timelines as irrelevant deviations.
