Sometimes I try to "zoom out" and look at Ukraine more in terms of a thousand-year view. When I do that? It's like... Russia is the meniscus in your knee. It's a shock absorber, the space in between Europe and Asia - geographically part of both, geopolitically maybe part of neither - where a ton of friction and conflict happen.
The core of the meniscus is, well pick a name. Muscovy, the Kievan Rus, the Rurikids. But it's been there for 1,000+ years, so maybe it's a bit myopic and short term to think of it solely in terms of Putin Bad, Zelenskyy Good, even if that's pretty much true from a bunch of really solid perspectives. Russia would be insane *not* to look west, south and east like there are enemies at the gate. Historically, there pretty much always have been and it'll go on long after Putin and Zelenskyy and all of us are long dead.
The Crimean Khanate was a remnant of the Golden Horde; the Mongols invaded something like 700-800 years ago and stuck around in some capacity for a few centuries. Russia has had wars with the Ottomans (Russo-Turkish wars). They've had wars with Europe... France invaded, Germany invaded more recently, they've got centuries of history of war with Sweden.
Sometimes Russia's the aggressor, and they're not saints by any stretch of the imagination. See: the Circassian genocide, the mass deportation of Crimean Tatars, this war, and on and on. "Denazifaction" of Ukraine is a clear pretense to hanging onto the Russification of Ukraine. Which is what it's really about... keeping a buffer of vassal states insulating "real" Russia from the forces beyond it. Putin wants Ukraine to be a Russian puppet state, instead of a European one. The same way Crimea was an Ottoman puppet at one point, or Kazan was an alternating Russian-leaning or Mongol khanate. The long game seems like "keep the fight out in the yard and off my porch".