Love and like are difficult to translate into French because aimer can mean many things depending on the sentence:
Aimer can mean love when you use it to describe your feelings for someone you really feel close to. Example: J'aime ma femme. = I love my wife.
Aimer can mean like when it is followed by the word bien. In that case, aimer's meaning loses a little bit of it intensity: you still like something or someone, but not as much as something or someone that you love. Example: J'aime bien mes collègues. = I like my co-workers.
Sometimes, the word bien is omitted, but you can guess by the context what aimer means. Example: J'aime le chocolat. = I like chocolate. / J'aime mes enfants. = I love my children.
The other problem is that aimer and adorer should not be confused because they do not describe the same type of feeling: aimer describes the type of affection that you have for someone, whereas adorer describes the joy that you feel when you spend time with someone.
Je t'adore. could be translated as I love you [because I feel very joyful when I'm around you]. You could say that to a very close friend.
Je t'aime. could be translated as I love you [because I feel very close to you, I admire you and I want to share my life with you]. You could say that to your boyfriend or your girlfriend.
I hope that it was helpful. If it is difficult to understand me or if I wrote something wrong (English is not my mother tongue), please tell me ^^
It is true that the sentence "Nous aimons nos parents." is rather ambiguous. If you want to emphasize the fact that you only like them, you can say: "Nous aimons bien nos parents." Adding the word "bien" after the verb "aimer" shows that you have affection for your parents, but it is only a decent form of affection.
Go to the "French" section once you have clicked on the link below. It should lead you to the page "How to pronounce nos" on the website "Forvo". There are three different people who posted their pronunciation of the word "nos" (which are all correct in my opinion) as I am writing this.
In French, the word "parent" refers to one's parents, so to the people one's considers as their mother and father. It can also refer to a single parent, but it is not only used in that case.
Basically, "to love" describes a stronger affection than "to like". I do not think that translating "Nous aimons nos parents." as "We like our parents." is wrong because "to love" and "to like" both mean that you are emotionally attached to someone. For me, there is not enough context to say if the people speaking "love" their parents or only "like" them.
In addition to that, in many cultures, people consider that the members of one's family are the people with whom one has the stronger relationships, especially the parents. I think this is why Duolingo may consider it wrong to type "We like our parents.", but you could say "like" if this is how you feel about your family.
"Aimer" means "to love". If you translate "Nous aimons nos parents." as "We like our parents.", you imply that what the people talking feel is not as strong as love. To keep the idea that they have strong feelings for their parents, you should translate "Nous aimons nos parents." as "We love our parents."
If you want to use the verb "to like" in French, you can add the word "bien" after the verb "aimer".
"We like our parents." -> "Nous aimons bien nos parents."