People have differing formative experiences, different upbringings and personalities. All these different factors affect their values and motivations.
For example, in a fantasy novel where characters go on a dangerous quest, one might be a money-hungry assassin who is in it solely for the pay and extravagance. Idealism and nobility are of no value to them. They’re practical and calculating, unfeeling.
Another in the party, meanwhile, has a restless spirit. They’re just tagging along for the adventure and can’t bear to be in one place too long. What's really important is that all characters fill their own niche, such as The Big One, The Small One, The Funny One, The Spiritual One, The Old One, The Young One, The Lancer, The Untrustworthy One, The Brave One - Just some examples. Another example would be
@Lady Bloody Ava's Dolly's sharp contrast to MC, Elisa. It creates an easy lance between the two and gives plenty opportunity for character deepening and development. When everyone is vital to the whole, it creates a more interesting and likeable narrative.
As you populate your story with its own unique cast, it's important to consider the extent to which they do the same, and consider incorporating some aspects of the types above. I mention this because I feel like we're not in that predicament. No characters seem samey and all seem to have varying ideals, or lack thereof, if you will.
The lancer (referring to an ideological foil to your character). Though they often share goals, and maybe even a friendship in the long run, they go about things in very different ways. A great example of this is Deku and Bakugo from My Hero Academia. They both desperately want to become the number 1 hero, but tackle the task in counter opposite ways. Deku is cool, collected, calculated and thoughtful in his approach while Bakugo is hothead, vile, brutish and cruel.
That being said, MC is captivated by the thought of studying and researching the world around her first hand, meaning she will be on the prowl for new intriguing species and samples, constantly moving from environment to environment, perhaps unearthing critical information of her surroundings in the doing.
Again, to use Dolly as an example. “Now the young woman wandered the lands doing performances and talking to peoples "loved ones" to get by. “It creates a relatively seamless reason why they would travel alongside each other. Company’s always nice (Obviously depends). Perhaps Dolly joins just to bother the others (I want to clarify that these are just examples, I don’t know the character well enough to judge. Don’t kill me!), maybe she secretly hopes that Elisa can somehow help her mental state (Not that she necessarily wants to have it relieved)
And I just realised how much I wrote. My bad xD