There were quite a few black combat units in the U.S. Army during the war.

The black soldiers who saw combat were volunteers, draftees, or National Guardsmen from northern states who'd been called up. Although many of these men ended up in support units, some did see combat. There were two large frontline formations that were mostly black: the 92nd Division and 93rd Division. The 92nd fought under U.S. Army control and had four infantry regiments, three field artillery regiments, a trench mortar battery, three machine gun battalions, a signal battalion, an engineer regiment, an engineer train, and various support units. Most of the junior officers were black, although senior officers were white.

The 93rd (which the 369th Infantry Regiment was part of) was attached to the French, since some white American troops refused to command or work with the black troops. Also, the French were clamoring for manpower, so the black soldiers were a much-needed and welcome reinforcement. The 93rd had four infantry regiments, three of which were comprised of National Guard units from New York, Illinois, Ohio, Maryland, Connecticut, Massachusetts, the District of Columbia, and Tennessee. The 93rd never fought as a complete division and its regiments were paralleled out to form units like the French 157th Infantry, which was formed from the French 333rd Infantry Regiment and the American 371st and 372nd Infantry Regiments on July 4th, 1918.

You can read more about how the two divisions faired in this article.

Most if these black units saw comparatively little combat compared to some other American infantry divions. For example, 92nd Dvision's only major battles were during the Meuse-Argonne Offensive of September-November 1918. During the war, the 92d Division took 1,647 battle casualties (dead, wounded, missing, and captured) while the 93d Division sustained 3,534 casualties.

By contrast, from May 1918 to November 1918, the American 1st Division had lost 22,668 men killed, wounded and missing. The 3rd Division, the "Rock of the Marne," lost 3,177 men killed in action and another 12,940 wounded in action.

All in all, of the roughly 2 million men in the American Expeditionary Force, around 350,000 of the soldiers were black, most doing menial labor in rear areas. Of these men in uniform, 320,000 were killed and wounded, including 53,402 battle deaths and 63,114 noncombat deaths, mostly due to accidents and disease. After the war ended, another 25,000 Americans died in the 1918-1919 Spanish Flu epidemic.

Of course, the Americans weren't the only ones in the war.

The Indian troops in the British Indian Army and France's African colonial troops fought in the war from beginning to end, and suffered substantial losses. During the Great War, France called up 8.317 million men, amongst them including 475,000 colonial troops, mostly from Africa. All in all, France and her colonies lost around 1.4 million men killed. With about 1.35 million French-born dead, metropolitan France had about a 17% death rate amongst its soldiers

In the war, around 81,000 to 97,000 French colonial troops died, including 26,000 Algerians and 30,000 Senegalese Tirailleurs. In the case of the Senegalese, nearly 200,000 of them served in uniform and 135,000 went to France to fight. All in all, 15% of the Senegalese soldiers were killed in the war.

In the case of the British Indian Army, over a million Indian soldiers served in Africa, the Middle East, and Western Europe. Nearly 75,000 died of combat and non-combat causes, a 7.5% mortality rate.

By contrast, nearly six million British men were mobilised, and over 700,000 were killed, a death rate of around 11.5%.

The tendency of Western armies to use non-white troops in service roles or using them in far-flung, low-intensity corners of the war (ex. the African Campaigns) may be one factor in their lower overall loss rates. Although it's worth nothing that Indian and African troops also fought in some of the toughest fighting on the Western Front. Visitors to Vimy Ridge and Verdun will see memorials and graves of the thousands of North Africans killed fighting there. Many a cemetery in Belgium and France has markers with the names of Indians who died far, far from home.

In the American case, the late entry into combat for the 92nd Division and other black combat units was the major reason they took fewer overall losses than all-white units which had been fighting longer.