Does anyone know what this insect is and if it is the cause of the sick plant?
I'm not familiar with the exact species of beetle, but it is likely the cause of your issues. There are many ways to control beetles, though. This collection of articles will help:
https://www.gardeningknowhow.com/plant-problems/pests/pesticides
This article will help you with the care of your plant:
https://www.gardeningknowhow.com/ornamental/trees/brugmansia/care-for-brugmansia-outside.htm
ause I ket it in the house for the winter I live in zone 7
It will bloom, successfully, each year as long as it has the correct temperature, lighting, watering, and nutrients. This can be tricky for those that live outside of the shrub's zone, but can be done.
It must be old enough to flower, as well.
Here are some articles that will help:
https://www.gardeningknowhow.com/ornamental/trees/brugmansia/growing-brugmansias-in-containers.htm
My Angels trumpet has fading and small spots on the leaves. I’m attaching a picture for your review.
This can happen for many, many reasons, unfortunately! Lack of humidity, high heat, and lack of fertilizer are most common. This does not look like disease, but the picture is not quite clear enough to make out much detail.
You could take samples and photos up to your local extension service, and they can be of greater assistance. It will help to be able to see the issue in person.
https://www.gardeningknowhow.com/extension-search
This article will help you with proper care:
https://www.gardeningknowhow.com/ornamental/trees/brugmansia/care-for-brugmansia-outside.htm
I have brown colored decay spots on the angel trumpet flowers as they are blooming. I now notice the spots on the flowers before they open. The angel trumpet is in the ground and has been a healthy blooming plant for a couple years. The leaves are full and no spots on them.
It could be botrytis blight, a fungal disease. Thrips also attack buds. These articles should help:
https://www.gardeningknowhow.com/plant-problems/disease/treating-botrytis-blight.htm
https://www.gardeningknowhow.com/ornamental/trees/brugmansia/brugmansia-problems.htm