I was asked about this recently in an online forum where I was expressing my opinion that most voice teachers, especially at university level, are not familiar enough with easy repertoire that better suits a singer who is just beginning to study singing technique.
There is a lot of good material in the anthologies by Joan Frey Boytim. There are three distinct series edited by her for young people. In order of advancement:
1. Easy Songs for the Beginning (S,M/A,T,B) – Short selections in the middle of the voice. Some by famous composers, some folk songs, some old American parlor songs. I use this book with middle school kids, mostly.
2. The First Book of (S,M/A,T,B) Solos – Legit composers, usually with original languages plus singing translations. The “First Book” series has three separate parts (I, II, and III), sold separately. My high schoolers are required to work with these. I also have used these songs with the college kids and adults. It’s all legit rep of mostly medium difficulty. I like how she introduces foreign languages in short songs, which is better for beginners.
3. The Second Book of (S,M/A,T,B) Solos – Theoretically a bit more advanced, but as with the First Book series, the difficulty is rather varied. There is a Part I and a Part II, sold separately.
I also use folk songs. I’ll use very basic arrangements for the early teens, but for those who are a little older I sometimes use some of the Britten “Complete Folksong Arrangements” published by Boosey & Hawkes/Hal Leonard in High and Med Low versions. 61 songs with their original melodies and words, with only the accompaniments getting fancy. A mixture of British, Irish, and French.
Hal Leonard’s “Anthology of Spanish Song” has 9 arrangements by Kilenyi that are simple settings of folk songs in Spanish. Easier than most of the Italian 24, but lovely. There are a few other songs in this huge collection that are doable by young singers, as well as some warhorses like the de Falla Siete Canciones.
Purcell has some songs that are not too hard, with fun and clever texts that the students enjoy. I would stick to the simpler International realizations rather than the wild Britten (Boosey & Hawkes) ones.
I never start a beginner with Italian, by the way. Mother tongue first, then branch out. It only makes sense. That’s how the Italians did it! So I start with English or Spanish, depending on the person, then add whatever language they have studied in school, then start adding the Italian, etc. But I don’t fuss over foreign languages with young people too much until the technique is on its way. If someone starts with me at age 14 or 16, I don’t think it’s a problem to wait a year or so to assign Italian.
“Resonance™: A Comprehensive Voice Series serves as the official resource for voice assessments of The Royal Conservatory Music Development Program.” This is a progressive repertoire that works pretty well. Books 1-5 are good for beginners. There is an overabundance of languages, so on some of these I have bitten the bullet and used the English singing translations or skipped those songs. I really don’t think people need to be dealing with English, French, German, Italian, Spanish, and Japanese in their first year of study! They are updating the selections, so these comments might be outdated soon.
That’s a start. 90% of the above are good for beginners of any age, because it’s music of acceptable to excellent quality that isn’t technically taxing. I have included large collections with lots of material. There are many smaller collections or single songs that are useful.