The gazelle is not self-conscious about it's life, and whether it's muscles are beautiful or not. It will never sense the beauty of what you're describing - from it's point of view, it will just feel fear, pain, then die.
Perhaps a higher-dimensional being would also see some beauty in our life that we cannot comprehend currently - like the gazelle can't comprehend it's Olympic flow, a human can't comprehend the long-term beauty of how they toil and work against the odds.
> whose life is better?
If by better you mean, which being feels more emotion/happiness/satisfaction, it's an open question. But if better implies more progress and safety/longevity, then humans it is.
The gazelle may not be able to reflect on the meaning of its existence but it is certainly capable of experiencing its actions and environment. A lack of self-awareness is not a lack of enjoyment, it may even heighten it. Think of the droves of people working to afford some time to simply live in the moment, to experience the raw beauty of nature or a physical challenge. Without a self or ego projected into the future, every minute of the gazelle's life is like that. As you say, an animal can feel fear and pain but they are also capable of feeling relief, pleasure, and even joy.
If you attempt to quantify life in such terms you may run into issues, our longevity is meager when compared to a giant tortoise or a simple koi fish, for all of our progress and the safety it grants us we still succumb to the same fate, we still suffer and all of our works are washed away by rain and time.
Perhaps a higher-dimensional being would also see some beauty in our life that we cannot comprehend currently - like the gazelle can't comprehend it's Olympic flow, a human can't comprehend the long-term beauty of how they toil and work against the odds.
> whose life is better? If by better you mean, which being feels more emotion/happiness/satisfaction, it's an open question. But if better implies more progress and safety/longevity, then humans it is.