In Kentucky, students who have 3 or more unexcused absences from school are considered truant. Chronic absenteeism is defined as 17 or more excused or unexcused absences from school in a school year.
Truancy complaints can be filed by a school district when the number of absences are excessive - and fines can be imposed and charges can be filed against parents when their children have 9 or more unexcused absences.
Your son's school is concerned about him, and the concern is not an unreasonable one. That is why you were visited by the police and social services. You and your son can expect interviews with social service workers.
The goal in these interviews is not to punish either child or parent over the school absences but rather it is to identify the reason(s) for the student's absences and help find a solution.
You say that you have no transportation which I assume means you have no car. Do you have a driver's license? If your son misses the bus in the morning and you have no way to get him to school, how are you able to get your son to the doctor or go to grocery stores for food?
There are organizations that can help with transportation needs if that is a major issue, for example.
I do not see that your rights were violated. I DO see that you and your son may need some help addressing your son's truancy.
Good luck.