The correct way to say "German" in Spanish is "alemán" for the singular masculine form. This term is used both for the language and for a person of German nationality. For example, "Hablo alemán" means "I speak German," and "Soy alemán" means "I am German." The plural form is "alemanes," referring to Germans as a group. The other variations you listed like "germanse," "lemano," and "alemanse" are incorrect in Spanish.