I think it is more true to say the Church embraced and developed the concept of personal rights in the 19th and 20th centuries. Also, the church slowly (through the appropriation and development of natural, civil and Roman legal ideas) gradually developed a theory of legal rights and obligations and political theory, which was quite complex and rich by the Middle Ages. It has to be acknowledged this development of the law was very positive since it laid the groundwork for the development of the rule of law and constitutional documents like the Magna Carta and the limitation of the absolute power of monarchs. See A. Zimmerman, ‘The Christian Foundations of the Rule of Law in the West:a Legacy of Liberty and Resistance against Tyranny’
creation.com/the-christian-foundations-of-the-rule-of-law-in-the-west-a-legacy-of-liberty-and-resistance-against and also ‘The Rule of Law as a Culture of Legality’,
elaw.murdoch.edu.au/archives/issues/2007/1/eLaw_rule_law_culture_legality.pdf.
The church was initially quite hostile to individual rights, as the Popes of the time associated the agitation for individual rights and freedoms as a seed for social instability and anarchy against the common social good, and that as Catholicism was the only true religion, dissent (as experienced by the schism sparked by the Reformation) expressed by freedom of speech or freedom of conscience in matters of religious belief or morals would be catastrophic. Nevertheless, Popes in the 19th century began to develop social teaching to deal with the problems caused by capitalism, including freedom of association, right to a just wage, and other rights.
The embracement of human rights continued strongly after Vatican II and Pope John Paul II was especially progressive in this area, especially on his condemnation of slavery as intrinsically evil (slavery had been acceptable for the Christian in past centures), his emphasis on the need to get rid of racism, inequality and inhuman working conditions, his positive teachings on the need to protect the integrity of the family as a social unit, and his desire to protect the sacredness of human life.
I am not sure if there is a Catholic theory of human rights as such, though I think in the past 150 years the Church’s Magisterium has developed a social theology that embraces and promotes certain rights (i.e. the right to a just wage, the right to marry, the right to procreate and educate children, the right to religion, the right to follow one’s conscience, etc). I think despite some of the darker aspects of the social theology of the church (such as the crushing of conscientious dissent among theologians like Charles Curran or Hans Kung, the continued ban on contraception, and the hostility often made against homosexual people or advocates for women’s ordination) this development is very positive and good for society as a whole.
Some good books on Catholic social teaching include the works by Charles Curran, John T Noonan Jr and Pope John Paul’s social and family oriented encyclical letters are good expositions of Catholic social rights teaching, but they should also be read in light of Pope John Paul’s ‘Veritas Splendour’ which also sets out the normativity of natural law and its the limitations it places on rights and the obligations definitive laws and moral norms impose on Catholics and the wider human society if a just social order is to be achieved.