The "ELI5" meme needs to die, it does not make any sense in most of the situations it is used, and also it's a self-disgrace to anyone using it to compare their own intelligence and knowledge to that of a five year old.
Gravity pulls you down to earth. It gives you weight. Without gravity everything on earth would start hovering and flying around like on the space station. Things in space near earth also get pulled towards earth.
Orbit is if you throw something so very fast that it doesn't fall back to earth but instead moves on a circle around earth like if you have a stone on a string and spin it.
On the moon you can throw a stone very far. On the moon there is no atmosphere that slows it down. If you throw the stone harder and harder it will fly very far until it gets dragged down by the moons gravity. Maybe use a cannon to throw it very fast it will fly past the horizon. If you have just the right velocity it will fly all the way around the moon and hit you in the back of your head.
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I think this topic is something that can be explained very well to kids. Also many kids are fascinated by rockets and space. The explanations and visualizations may not always be 100% accurate but I think they do the job.
But you've been caught into a hole you (and grandparent poster) have dug for yourself, by trying to explain it fully. A better explanation for a five year old would be something like: satellites all fly high above us, and we are putting more and more satellites up there, and eventually they will crash into each other, and then into other satellites, and so on, until there is nothing but broken satellites flying up there.
If the kid is interested and has more questions about "how" and "why" (the favourite world exploration tools for every kid), only then it's time to introduce him or her to gravity , the fact that Earth is round, and the basics of orbital mechanics.
But all that aside, what nerd kid wasn't drawing space shuttles and rockets by age 5?!? That was my jam!
"ELI10" or "ELI15" would be a much less ridiculous request. It's still rather grating how people willingly denigrate themselves by comparing their own intelligence to that of a child's.
What's wrong with good old "explain it to a layperson"? The fact that it does not make a cool acronym? We're not on twitter (or in high school, for that matter), learn to express yourself like an adult.
And yes, I am fun at parties. :)
No need to overthink it.
"A meme is an idea, behavior, or style that becomes a fad and spreads by means of imitation from person to person within a culture and often carries symbolic meaning representing a particular phenomenon or theme."
Contrary to what Internet would like us to believe, a " meme" is not a picture of a cat with some written words around it.