I think I'd start by commissioning some experts to come up with a whole load of vignettes of fictional kids, with a wide range of characteristics reflecting the differences and needs kids might have.
Like:
Child A: average early development, average academic potential in all subjects, may go off the rails in the wrong environment, if given the opportunity will develop an interest in history, significant visual impairment, supportive family background.
Child B: average early development, mostly average academic potential but will have aptitude for sciences if given the opportunity, dyslexic and even with the best circumstances won't learn to read before age 9, supportive family background.
Child C: delayed social development, top 1% academic potential in all subjects, susceptible to mental illness in teens if subjected to prolonged stress, English as a second language, chaotic family background
Child D: average early development, well above average academic potential, will be prone to doing the bare minimum and coasting unless encouraged and given competition, will be involved in an accident and require months away then return with significant mobility needs, supportive but resource-poor family background.
Child E: average early development, lower than average academic potential, given the opportunity will develop an interest in business, supportive family background.
Plus lots more, including several fairly unexceptional imaginary kids (but with their own potential quirks and personalities), several with significant disabilities or SEN, different circumstances and personality types and so on, all of whom could have very different trajectories depending on what education they're offered.
Then I'd commission other groups of experts to design the ideal educational and developmental "journey" (ugh, sorry) for each of these fictional children, which would maximise their potential, be least likely to cause harm, and leave them as prepared as possible for the next step Like, maybe, child X would do best with a supportive, play-based environment until age 6, then a nurturing and noncompetitive school initially focussed on literacy and life skills with access to academically-demanding modules on specialist topics within a range of subjects, while child Y would do best with a highly structured environment with strict expectations from preschool on, with rigid rules and regulations. Or whatever. I don't know, that's why I'd be asking experts.
Then I'd get some more experts, show them the dossier of imaginary students and the ideal educational pathways that the other experts had designed for them, and tell them to create a school system that would near as dammit facilitate the right environment and trajectory for all the imaginary students, starting by working out how to identify these needs and flexibly adapt to them throughout.
This is a long-winded way of saying that I think the problem is that we design a school system and then try to fit the kids in it, when we need to look at the kids we have and fit the schools round that. Somehow. I don't know how, that's what I want the experts for 