I’ve heard there are three or four other species that are similar to humans that all died out; is there a Biblical explanation for these other species?

The most common ones talked about are “Cro-magnon” and “Neanderthal.” The impression presented has always been of subhumans or something similar to, but less than, humans—some part of the evolutionary process. That is actually not the case. One of the scientific advances made recently is the ability of scientists to map out the DNA strands of ancient people through the remains that have been found. In the case of Neanderthal, remains have been found in several different sites on different continents—from Spain to southern Siberia and from Germany to the Middle East—more than enough to allow accurate generalizations of those particular people. One discovery: 99.7% of the DNA mapped from Neanderthal was identical to modern human DNA. Both Cro-Magnon and Neanderthal exhibited larger builds than modern humans. But more to the point, they exhibited much the same behaviors as do modern humans. Neanderthals, for instance, very carefully buried their dead. Hunting was done in community, and they left behind complex tools. There is evidence from Cro-Magnon that they sewed garments or wove baskets, and they left behind world-famous artwork that can be found in caves in France, along with intricately detailed javelins, arrows and other artifacts, often with carvings and designs on them; an ivory pendant made from mammoth tusk was found in south Wales. And a discovery in the Czech Republic told us that Cro-Magnon may have had dogs as pets. What appears likely is that these and other groups of humans were part of the post-Flood, post-Babel migration of people groups all over the planet. But, as apologist Ken Ham points out, “When God created humans, He didn’t define our humanness in terms of physical characteristics. We aren’t human because we have two arms or legs or skulls of a certain shape or size. Our Creator, who is spirit, made us in His spiritual image.” As Genesis clearly teaches, Then God said, “Let us make man in our image, in our likeness, and let them rule over the fish in the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground.” So God created man in his own image, in the image of God he created him; male and female he created them. God blessed them and said to them, “Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish in the sea and the birds of the air and over every living creature that moves on the ground”—Genesis 1:26-28. What does that mean? Genesis tells us: Our early ancestors made musical instruments and tools, farmed, built cities, and otherwise took their place in God’s creation. Early men have been discovered to have divided up jobs to prepare food; some took to sailing the seas. Ultimately, they provide more evidence of the wide range of variance in the individuals to be found in our wonderfully unique race.
Why did they die out? Following the dispersing of the world’s population as occurred as a result of God’s intervention at the Tower of Babel (So the Lord scattered them from there over all the earth, and they stopped building the city. That is why it was called Babel—because there the Lord confused the language of the whole world. From there the Lord scattered them over the face of the whole earth—Genesis 11:8-9), some groups would have moved off and become more and more distinct. As would happen to such a population with no outside influences (such as marriage), it is possible that, essentially, inbreeding created defects in their particular genetic makeup that caused their unique people group to disappear. What actually happened to Neanderthal, Cro-Magnon and similar people groups is still a mystery, and scientists are still exploring different theories of what might have eventually happened to them. But what we can know is that they were God’s creation, part of the people derived from Noah’s descendants following the Flood. And, because they were, as us, created by God, as David would say centuries later, I praise you because I am fearfully and wonderfully made—David, Psalm 139:14a