“raised up a savior.” There are many “saviors” in the Bible. God is the savior, and He often works through human saviors.
“Othniel the son of Kenaz, Caleb’s younger brother.” Although the reading of the text can be confusing, it is saying that Kenaz was Caleb’s younger brother, and Othniel was the son of Kenaz, and therefore Caleb’s nephew. Caleb was the son of Jephunneh (Num. 13:6), so the natural understanding of the text would be that Kenaz was also the son of Jephunneh (although sometimes “brothers” had the same mother but different fathers if a father had died). So from the information in the text, we can discern that Caleb and Kenaz were brothers and Othniel was Caleb’s nephew.