Okay but... what does this actually look like in practice?
Expertise in Investigation, sure.
Expertise in Air Vehicles, okay
Expertise in Land Vehicles, cool.
So... shadow monk or rogue? Let's stick with Rogue, he's mundane after all.
- A Top 10 martial artist on the planet
Oh dang, that's just monk. Maybe use the Fighting Style at least?
- An dabbler in multiple sciences and histories
So... skill prof in history and "arcana" since that is the closest we can get to science.
Let's ignore the convolution of the "top 10 martial artist" for just a moment. How could we possibly get Expertise in a single skill, two other skills, and expertise in land and air vehicles?
Uh... two levels in Rogue? Okay,
technically you only need a single level in rogue to get all of that, but Batman is very fast and sneaky, so I gave him the second level so he can have Cunning Action. Oh, and
technically you can't get tool expertise like this from Expertise, but I've never met a DM who wouldn't let you downgrade like that, so it should be fine.
So, get the tool proficiencies from his background, he also gets Thieves Tools which covers the that.
Total of 7 skills, let's put Expertise in Investigation with the Skill Prodigy feat, which also gets us another skill. Stealth, Sleight of Hand, History, Perception, "Science", Medicine, Athletics? That covers more than you even stated.
Now, I'm sure you'll start coming up with "well actually!"s to say that I totally forgot that Batman can also [blank!] but even if you get me up to level 6 or 8 as a rogue... that's kind of it. Variant Human Rogue covers a huge swath of batman's skills and abilities, most of which would be seen as... utter wastes of time for most players. They wouldn't take land and air vehicle expertise, because that is frankly not worth it. Then they can get expertise in Stealth and Perception.
The thing is... low-level DnD characters are ALREADY highly skilled, polygot warriors who have mastered a wide variety of forms and techniques. People just insist that they aren't.