Well, you should just accurately title your videos - if all your videos are about learning colors and Disney Cars 3, then so be it, although a little bit of programming diversity probably wouldn't hurt. It's a catch22 though as if you've built an audience that wants that one thing, you could alienate them by adding variety. I do some work for another channel that is in a similar sub-niche to you and I'm always surprised by how hard it is to straddle this line.
My agreement with Crown is about stuffing keywords in your description- that's a big no-no. Also, trying to fit a ton of keyword phrases into a title probably isn't a useful strategy anymore, anyway -whether its against TOC or not. I would focus on just 1 or 2. Your content is categorized more by viewer behavior than meta-data. If "Learn colors" and "Disney Cars 3" aren't the main draw to your video then you could probably just leave those things off. Or, if you basically do tons of videos that are exactly about those two things, you could try numbering them... ep.1, etc. I don't have any evidence that this is helpful, but it can make your titles seem less repetitive if you are concerned about that. I was given the advice by my YT rep that putting your channel name or some part of it in the title may be helpful for surfacing on the Kids app. Not sure whether I believe this, but you can see this trend in many large kids channels over the last year.
If you want to talk more about this we should start a new thread or you can PM me.