I applaud your effort. More of this is certainly needed.
There is one... question, if you will - perhaps a criticism, I'm not sure even myself.
"Age-appropriate"... sticky term. It's just that I have a very different sense of the term. It is my firm belief that children should be spoken to more or less as adults. If we go back 150 years, children in fifth grade read Milton and Shakespeare, for example, and understood. I daresay there is no such child anywhere on the planet to be found these days.
Why is that?
The answer is simple: the tyranny of low expectations. THAT is something you should be teaching to not just children, but to parents, especially that particularly timid breed referred to as the "helicopter parent".
In days past, young people were expected to comport themselves as adults at ALL TIMES. That did not preclude play and fun. Very much the opposite. But when they were in the company of their fellows, especially the adults, they were expected to behave in an adult manner. That produced strong, intelligent, proper adults rather than the toddlers in grown-up bodies that today we call "millennials".
If this book is meant to be read to toddlers, I would call it well enough, though I would also strongly recommend parents of good sense and character also read adult works to them, even if they do not understand. Understanding comes with time and I would warn all parents against anything more than token amounts of "baby talk". I firmly believe, through a lifetime of observation, that speaking to children as if they are children, or worse - imbeciles - sets a tacit standard; a very low standard to which the child is put to aspire.
Progressives and other tyrants of the "modern" era have well been aware of the need to reduce men to a status of nitwit children in order to be able to command them such that no amount of arbitrary stupidity will be met with anything more than blind compliance. We have gone far down that path, but perhaps not yet too far. Thin as it may be, hope remains and if you can get through to parents, enough parents, the tide may yet be altered. We only need a critical mass in order to survive and, eventually, prevail through the restoration of strength, intelligence, and proper human relations as the common norm, even if only as a "black market", closeted subgroup.
Those gloomily extreme possibilities aside, if you want to seriously make a dent, then dent the parents, because so far as I can determine there is a huge plurality of them who have absolutely no clue as to how to properly raise a child. The litany of errors to which a disturbingly large proportion of contemporary parents subscribe themselves is astonishing, not to mention deeply depressing, leaving little wonder why children now grow into weak, ignorant, grasping, and feeling entitled.
Parents have got to retreat from weakness and the demand for guarantees of safety and other outcomes for their issue. Thus far, I see little to no evidence of this in the populations centers, the bastions of progressive toxicity. Rural America is not as bad, but even here in West Virginia I see the creep of progressivism in places. It will be the death of us.
Raise the expectations to which children are taught to aspire. Convince parents of the virtue of this, as well as those of the full monty, if you will, of freedom; that freedom isn't just the right to put one's willie where he pleases, but demands the best of a man, the acceptance of risk, and perhaps above all else, respect for the equal and valid claims of one's fellows.
My worthless opinion on the matter.
Cheers.