Pierce Brosnan, Aldis Hodge, and Quintessa Swindell all look fantastic in their hero roles, but I can’t tell you who these heroes are.
Based on the scene, I would think Marilyn and Charles “C.C.” Batson, Billy Batson (i.e., Shazam / Captain Marvel)'s parents, and Saied, a liaison with the Egyptian government for an archeological dig. In the comics, or at least in “The Power of SHAZAM!,” the parents and Saied were murdered by Adam, who was actually Teth-Adam, the second Shazam, reincarnated and … yeah, I can see why they might just cut all that down to “they broke the seal and Black Adam murdered everyone there.”
I think that the titular Black Adam is basically bad Shazam,
Sort of? The best versions have him as very well intentioned, and overly protective of his people, but also very ruthless and willing to kill those that oppose him without hesitation. His methods are somewhat evil, but his motives are much less so – a noble character in the original sense of the term.