It's as much the order of the ingredients that you want to look for and the overall balance of the formula and your routine. Be aware that the first five or so ingredients are the most important because they make up the bulk of it. In Europe all products will be in order of how much of each ingredient is present, not sure what the US rules are but certainly the big players follow this system.
Check out the 'curl chemist' series of articles by Tonya McKay hereon NC for ingredients lists and further explanations. If you get totally confused feel free to start a thread linking to an ingredients list and asking for comments - there are a few of us 'geeks' here that quite like analysing ingredients.
Many products the first is water, then in a 'true' conditioner you'd see perhaps two to five of the major emollients (fatty alcohols and/ or cationic surfactants) the next few ingredients. Further down the list there might be proteins, humectants or oils. Anything that is after fragrance or preservatives is likely present in very small amounts.
In a product that is more of a moisturiser you might see a major humectant high up the list, perhaps as the second or third ingredient. If a product had two or three oils or butters and one fatty alcohol in the first five ingredients again you might consider if it is a true conditioner, more of pomade or finisher (like a CG serum) or how heavy/ greasy it is.
Some products are more of a detangler, these might be a spray or watery liquid product containing a lot of silicones or film formers. One CG example is Kinky Curly Knot Today.
There is no magic number and there is an element of personal judgement/ subjectivity. Even when you choose a product based on ingredients there is no guarantee you will like it, you are just aiming to narrow your options and giving yourself an increased chance of success. It also helps you understand why a product doesn't work for you, or only works for you in certain dew points/ humidity. Don't forget that even if you had identical twins with an identical routine, one might prefer softer more volumised waves and the other more clumpy well defined curls.
Protein craving/ sensitivity: personally I think it's more of a spectrum and the the polarising is unhelpful, we too often see people claiming ingredients are proteins or act like proteins when that is is not the case. There are good science-based articles on hydrolysed proteins on both Natural Haven and by Tonya McKay. Hydrolysed proteins patch repair, can penetrate, strengthen, act as film formers conferring shine and helping the cuticle lay flat, are mild humectants (can draw water to and out of the hair), volumise, can build up and stiffen or dehydrate the hair.
Those with damaged hair benefit (patch repair, strengthen, film former), also those with fine hair (strengthen, stiffen, volumise). Those with coarse hair tend not to do well - that hair has plenty of its own protein and don't need stiffness or volume. If the coarse hair is either dry or low porosity then dehydration or build up may be a particular issue. In very low dews any humectant, including protein, may draw too much water out of the hair, in very high ones any humectant may draw too much water into the hair. This obviously interacts with the hair properties.