You just said using these terms 'infantilises' AI... You can't infantilise something that isn't a person beforehand, now who is humanising it?
The point is, computing has always borrowed everyday words for technical ideas. That's metaphor, not a claim that the machine is a person or a child.
In security, a sandbox is a sealed-off space where code can run without touching the rest of the system. It's a test place. The idea is containment: the sand stays in the box. The term has been used this way since the early 1990s, and Java made it mainstream in 1995. It's about keeping untrusted code fenced in, not about toddlers.
There are many others too!
Parent and child. When one program starts another, the first is the "parent process" and the second is the "child." This goes back to Unix in the 1970s.
The same family includes "orphan" processes (the parent has ended), "zombie" processes (finished but not yet cleaned up), and a command literally called "kill." Nobody thinks a server is grieving or haunted.
Pipelines. There are no pipes. In Unix, a "pipe" passes one program's output straight into the next, like water through plumbing. Chain several together and you get a pipeline. It's just a picture of the flow.
A few more, a "daemon" is a background program, named after Maxwell's demon from physics. Data structures have "trees" with "roots" and "leaves." Unused memory gets cleared by "garbage collection." There's no bin lorry.
None of this means people thought data was human in the 90s. It's just general terminology used in coding.
So "sandbox" says nothing about whether AI is a child. It's an old, ordinary piece of computing vocabulary, older than most of the people now using it.