Here I will make a simple analogy.
Space is curved, so imagine that the sun is a massive object, the space near it is "dense", and the space far away from it is thin. The closer to the star, the slower time will be, and the farther away from the star, the faster time will pass. Similar charges produce an electric field. The closer the charge is, the stronger the field strength is, and the farther it is, the weaker the field strength is.
When an object enters a "space with uneven density", it moves along a curved route in our senses, just as a bullet enters water from the air and is refracted due to density change.
Because the farther away from the sun, the thinner the space (please forgive me, this is not tunnel, just for illustration), the closer to the sun, the slower the time, the gradient of space (rate of change) and the gradient of time (the closer the star in the room, the slower the time passes), then the object gets a trend in this gradient: the downward movement trend, and an acceleration A is obtained. (Have you learned it in middle school? Divide displacement by time to get speed, and then divide it by time to get acceleration, which is the rate of change of displacement rate. Sensory effect is feeling as if there is a force pulling objects towards the stars.
This acceleration is not uncountable, it is inversely proportional to the square of the distance to the star, and the direction points to the center of mass, which is proportional to the mass of the star. When the earth moves in this space, its trajectory depends on two factors, not only the acceleration a, but also the initial velocity v of the earth. If you want the earth to draw a perfect prototype, after the distance between the sun and the earth is fixed, can V be taken at will? Of course not, v must also be a constant value (not only the size is determined, but also the direction must be tangent to the circle, which is very harsh). The earth has only one circle when it runs in this V, and a slight deviation will turn it into an ellipse. If the speed deviation is too large, the earth will draw a parabola and fall to the sun or fly into space. (See First and Second third cosmic velocity)
Besides, I am not a great god or an expert. I'm just telling you the limits I know. I hope you are stronger than me.