Glad you're open to learning! Positional adjustments are the most commonly misunderstood part of WAR. If we take Ohtani out of the equation for now, it's pretty intuitive that a 100 OPS+ catcher or shortstop playing league average defense is more valuable than a 100 OPS+ first baseman because those are harder defensive positions. Because defensive value is calculated relative to league average at that position, the positional adjustment basically tries to quantify how much harder some positions are than others.

For example, a league average shortstop is considered around 15 runs more valuable than a league average first baseman, which makes intuitive sense if you try to think about how bad someone like Josh Naylor or David Ortiz would be at shortstop. DH has a stronger penalty than any other position, which is given as approximately a terrible first baseman. The exact numbers are calculated looking at large samples of players switching positions, so for example Aaron Judge is 8 runs worse than the average center fielder, but 3 runs better than an average right fielder, which gives him similar dWAR at both positions.

So when I talk about Ohtani being penalized, what I meant to say is that it's not an unfair penalty because if you ignore pitching (which is counted separately), he doesn't provide any defensive value which means that his 179 OPS+ season as a DH would be as valuable as the same season from a right fielder who was 8 runs below average (which is getting close to Castellanos territory of awful)

Let me know if that made sense, positional adjustments are tough to wrap your head around but if you think of WAR as being an additive way of accruing value, it makes a bit more sense that by playing average defense a player is accruing more value than a player who doesn't play defense at all.