Who's going to charge him with a crime? Iraq and Afghanistan both have the most to gain, but good luck getting the U.S. to extradite a former president to sit trial for a foreign power. The U.S. sits on the United Nations security council, so the U.N. can't do anything. Realistically the only one who could charge him is the U.S. themself, but that would require a formal admission that the wars were unjust. Not to mention, we're already struggling to arrest a former president who attempted a coup, and potential charges against Bush would be much more difficult.

Regarding Iraq: Because he cynically played enforcer for a lot of very rich (AKA influential) people who were scared that the US petrodollar hegemony was about to be supplanted by the Euro once people did the maths on Hussein's recent successful pivot to Euro as reserve currency https://ratical.org/ratville/CAH/RRiraqWar.html - notice how the puppet government that was then installed made it one of their first tasks to switch the country's reserve back to USD. The ongoing currency war was and is the actual war behind the "war" (wars).

Regarding Afghanistan: Everyone knew there was just too much "fog of war" to build a slam-dunk case against him for it. At best it would have ended up being framed by media as hand-waving about "wrong country" or "not just that country". I remember scratching my head wildly though when he was spouting his "with us or against us" and "bomb them back to the stone age" rhetoric (and going unilateral - with the help of his Blair poodle - when the UN disagreed). He raced straight past "un-presidential" on his way to "extremely childish" when conflating "surgically remove some known terrorists from their hiding places" with "go all scorched earth on the entire country where they might have last been hiding". There might have been some chance of making a case for recklessness (similar to the distinction between "manslaughter" & "murder") - on the part of a jumped-up cowboy-wannabe playing "war president", all hubristically drunk on the power he effectively inherited from his dad. As mentioned in many of the other comments though the US would never "allow" the ICC to bring such a conviction (undermining what the ICC is for), and any legal attempt within the US would just trigger screams of "you're not a patriot" and "too soon" (still).

Ahh god dammit. Yep... Happened when I was a kid, still furious.

I don't know dude, but I'm pretty sure I'm going to die mad about it.

I also want to know. Same with Tony Blair. Alas, I'm not a legal scholar.

Afghanistan was a just action. Let's just get that settled.

Iraq was legal but the public was lied to about the justification.

War Crimes requires a nation to purposefully target and kill civilians. If such an illegal order occurs those responsible are charged. If a government does not charge those issuing illegal orders they can be charged with War Crimes.

Civilian deaths do occur in War, a nation must only target legal military targets. For example the World Trade Center was an illegal target on 9/11. The Pentagon was a legal target on 9/11. Attacking a Civilian office gave the United States legal rights to retaliation.

As for Bush, his actions didn't violate international law in Iraq. They were questionable and diplomacy would have been the better option, but still not illegal. All acts deemed War Crimes had those responsible charged and sent to prison. For example those responsible for the Abu Ghraib incident were charged, convicted, and sentenced to prison. The person to ordered the abuse and torture of prisoners was William Hayes II, General Council of the Department of Defense and authorized by Judge Brett Kavanagh, yes the same one that now serves on the Supreme Court.

Bonus, Ron DeSantis was responsible for authorizing torture at Guantanamo Bay.

If you want to charge people with War Crimes, start with the three who still are at-large from justice.