"A free man is killed for a free man and not for a slave; and a slave for a slave and a female for a female. The verse clearly prescribes the punishment of death. So if a slave is not killed for a free man, he must then be killed for another slave. Otherwise no one is getting killed and the verse is rendered meaningless

It is highly disingenuous for you to quote this as if it is from a tafsir, these are your own words except for the first sentence, where the tafsir is mostly repeating the words of the verse. "So if a slave is not killed for a free man, he must then be killed for another slave." These are your words, not found or implied in any tafsir.

"the free for the free, the slave for the slave, and the female for the female. was abrogated by the statement life for life (5:45)

Again, you are just quoting the verse. I am not clear on whether this verse was abrogated or not - however abrogation does not mean the abrogating verse is necessarily contrary, it can also be that it establishes a more general rule. For example, the famous verse stating you should not pray after drinking alcohol is abrogated by the verse saying you should not drink at all, which encompasses the command of the abrogated verse but it does not contradict it. In this case "life for a life" is more generally applicable across all peoples as 2:178 was specifically in reference to tribes establishing their own rules of "equivalent" retribution.